Most conventional high speed postage meter mailing systems include a high speed envelope feeder, a mailing machine, a postage meter cooperatively coupled to the mailing machine and a receiving bin or other suitable apparatus. Briefly, the envelope feeder receives a stack of envelopes or other mailpieces and feeds the individual mailpieces to the mailing machine transport system in a segregated manner. Each mailpiece is then delivered to an indicia printing station for postage indicia printing by the postage meter. Subsequent thereto, the mailpiece is discharged to a receiving bin or other appropriate apparatus. The system is designed to act as a continuous process.
The afore briefly described process has as one of its objectives the ability to accommodate various thicknesses in mailpieces. To facilitate this objective, it is known for systems of this type and related denomination to provide a deflectable mailing machine platen at the printing station. The mail machine platen conventionally includes a lower impression roller rotatably mounted thereto. The print drum of the postage meter is rotatably mounted in a fixed location and includes a surface flat. In the print drum home position, the surface flat is located in spaced apart radial alignment to the mailing machine impression roller to define a mailpiece receiving gap. Ideally, the leading edge of an incoming mailpiece to the indicia printing station is received within the gap at which time print drum rotation is initiated. The mailpiece impression region of the mailpiece then being friction secured tangentially between the print drum and impression roller. The platen is deflected in response to the incoming mailpiece a commensurate distance corresponding to mailpiece thickness. As a result, excessive loads generated by communication between the print drum, mailpiece and impression roller due to mailpiece thickness are ideally translated to a deflection of the platen.
It has been found that in such mailing system the ideal condition does not prevail, i.e., during the postage meter impression cycle, the print drum and supporting structure are subjected to substantial loading. In a worse-case, the mailpiece thickness is approximately equal to or slightly greater than the gap distance, wherein the incoming mailpiece is initially wedged between the print drum rearward flat transverse edge and the platen, slightly rearward of the mailpiece's leading edge. The wedge position of the mailpiece upon initiation of print drum rotation causes the print drum to experience excessively high loading to which platen deflection cannot adequately respond. As a result of the excessive loading condition of the print drum, which is transmitted to the print drum drive and support structure, premature motor and bearing failure is promoted. Meter failure is further hastened due to the harmonic nature of the loading and increased motor torque required to drive the print drum upon initiation of rotation. It is appreciated, that high system torque requirement carrying therewith the associated system degrading factor, e.g., increased power consumption, heat build-up, etc. In the worse-case, the meter unit itself may experience visually discernible harmonic deflection resulting in the generation of excessive noise.